The penetration of alkanes of different chain lengths in bilayers of A
OT in the system AOT/brine/n-alkane is investigated by NMR measurement
s. For short chains (carbon number N < 11), the phase is lamellar. For
longer chains, the phase is bicontinuous or lamellar depending on the
salinity. It appears that, for N < 11, the alkane molecules penetrate
easily in the AOT monolayers. For N > 11, when the phase is a biconti
nuous one, the answer is not so straightforward because the phase is i
sotropic. For the anisotropic phases which contain small amounts of a
long-chain alkane the solubilization of the alkane in the AOT monolaye
rs is very weak. Short alkanes (N < 11) behave like a ''good'' solvent
for the paraffinic chains of the AOT molecules and long alkanes (N >
11) like a ''poor'' solvent.